BIG BEAR LAKE, Calif. — Police spent all night searching the snowy mountains of Southern California but were unable to find the former Los Angeles police officer accused of carrying out a killing spree because he felt he was unfairly fired from his job. Authorities planned a midmorning news conference today about 80 miles east of L.A. at Big Bear Lake, where Christopher Dorner’s torched pickup was found Thursday. The area was under a winter storm warning, with snow falling and temperatures well below freezing. Local ski areas were open, but Bear Valley schoolchildren had the day off because of the manhunt. About 150 miles to the south, up to 16 San Diego County sheriff’s deputies spent the night surrounding and searching a rural home after a hoaxer reported Dorner was there. There were people at home but Dorner wasn’t one of them, said Lt. Jason Rothlein. Investigators have a pretty good idea who made the call and will seek criminal charges, he said. Though the focus is on the resort area, the search for Dorner, 33, stretches across California, Nevada, Arizona and northern Mexico. LAPD officers are especially on edge because Dorner, who was fired from the force in 2008 after three years on the job, promised in rambling writings to bring “warfare” to police and their families.